Vacuum polarization around cosmic strings in de Sitter spacetime

**Authors:** A. A. Saharian **Affiliations:** Institute of Physics, Yerevan State University,1 Alex Manogian Street, 0025 Yerevan, Armenia Cosmic strings are the most popular topological defects arising from the spontaneous breaking of fundamental symmetries in the early Universe. They are the source of a number of interesting effects in cosmology and astrophysics. An interesting effect is the polarization of the vacuum state for quantum fields induced by the non-trivial topology of the spacetime around cosmic strings. In the present paper we describe the combined effects of the straight cosmic string and the gravitational field on the local properties of scalar, spinor and electromagnetic vacua. The local de Sitter spacetime is considered as the background geometry. It is shown that the influence of the spacetime curvature is essential at distances from the string of the order of or larger than the curvature radius. A qualitatively new feature is the appearance of the vacuum energy flux in the radial direction with respect to the cosmic string.